Process of utilizing sulfite lyes.



' UNITED" STAT S PATENT OFFICE.

VIGGO DREWSEN, OF NElV YORK, N. Y., AND LAURITZ J. DORENFELDT, OF

' TRONDHJEM, NORWAY.

PROCESS OF UTILI-ZING SULFITE LYES.

SPECIFICATION forming part Of Letters Patent N0. 726,036, dated April 21, 1903. Application filed November 25, 1901. seria No. 83,649. (No specimens.)

To all whom it may-concern: other words, the spent liquors from both Be it known that-we, VIGGO'DREWSEN, remillssulfite and soda pulp mills-can be sidingin New York,borough of Rich mond,and utilized to ad vantage in our improved process.

State of New York, and LAURITZ J. DOREN- While in our former process referred to re- 5 FELDT, residing in Trondhjem, in the King covered soda (soda-ash) was mixed with the dom of Norway, both citizens of the Kingdom sulfite lye, we now mix therewith the spent of Norway, have invented certain new and lye from the soda-pulp mill. The theory of useful Improvementsin Processes ofUtilizing the new process is that the sodium sulfide con- Sulfite Ly-es, of which the following is a specitained in the lye from the soda-mill react with Io fication. l .the salts of the organic sulfonic acids con- This invention relates to certain iinprovetained in the sulfite lye and prevent thereby ments in the process of utilizing sulfite lyes, the formation from organic compoundsinthe I for which Letters Patent were granted to us lyes of the objectionable aldehydes. on March 7, 1899, No. 620,755, said improve- It is a well-known fact that in evaporating i5 ments being designed with a view of simplithe spent liquor from a soda-pulp mill there fying and cheapening the process and ad-aptis always a loss of atleast ten per cent. of ing the same for use in sulfite-pulp mills, soda-ash, while when the spent liquor from which are run in connection with and in p'rox. a soda-pulp mill is worked up with the spent imity to soda-pulp mills. liquor from a sulfite-pulp mill, which latter 7o 20 We have found by practical tests in-sulfiteworks with sodium-bisulfite liquor, and both pulp mills that the process heretofore pat- 'liquors are evaporated together the sodium ented could be simplified when the waste liqcontained in the spent liquor from the sulfitenor from soda-pulp mills was employed for mill is sufficient to cover the loss of soda-ash Working up the spent liquor of the sulfite from the soda-pulp mill, so that there is no 25 pulp mills. We have also discovered that additional expense for soda for the sulfitewhen the spentliquor from sulfite-pulp mills pulp mill, inasmuch as the soda used in this was utilized by our patented process, even mill is recovered and utilized over again in with an excess of alkali, acid condensations the soda-pulp mill. Oonsequentlybycarrying are produced which corrode the concentrat on the evaporation of the spent liquors from 3o ing apparatus, for the reason that when the a soda-pulp mill mixed with those of asulfitetemperature, and consequently the pressure pulp mill a very economical process is obin'the boiler in which the spent liquoris contained by which the spent liquors of both centrated, rises to a high temperature vapors mills are utilized and at the same time the are given 01f which contain aldehydes that polution of the water-courses in the neigh- 35 are decomposed when mixed with steam of boI-hood of the mills eflectively prevented.-

high temperature into alcohols and acids, and Forthis purpose our invention consists of as the latter cannot be neutralized in the a process of neutralizing, the waste or spent steam-space of the boiler'they are carried on liquors of sulfite and soda pulp mills by first with the condensed water, and consequently neutralizing the waste liquor from one mill 4o corrode the iron and the multiple-concentratwith the sodium-containing liquor from the ing apparatus. WVe have found that this other mill; second, concentrating the neugeneration of acids can be considerably detralized liquors; third, burning concentrated creased when the temperature or the presliquors; fourth, leaching the residuum; fifth, ture in the boiler is kept down; but this im treating the solution with burnt lime, so as 45 pairs the efficiency and economy of the conto render it caustic, and then draining oflf the centrating efliect. iVe have further found clear liquor containing the soluble sodium that where the spent liquor from a soda-pulp salts for use as cooking liquor in the sodamill is obtainable the spent'liquor from a sulpulp mill. v fits-pulp mill can be utilized with this alka- Our process is practically carried out as I00 50 line liquor without any formation of acid follows: The spent cooking liquor from asultaking place in the concentrating plant. In fito-pulp mill which contains sodium bisulfite is neutralized by an equal quantity otthe' The hot gases which are developed by the combustion are carried off. and utilized for heating purposes, preferably for heating the boiler or the vacuum-pan itself, while the inorganic residuum is leached with water. The solution thus obtained is treated with burnt lime, so as to render it caustic, and is then drawn off and added to'the cooking liquor of the soda-pulpmill, the solution containing all the soluble sodium salts.

Our improved process has a special advantage in such cases where sulfite and soda pulp mills are run in one establishment or in close proximity, so that the spent liquors from both mills are available for use. In this case the spent liquors from both mills can be utilized to great advantage by a comparatively simple process, the spent liquor from one mill being utilized for working up the spent liquor-of the other mill, the resulting liquor containing all the soluble sodium salts,

which are then returned to the soda-pulp mill for being utilized as cooking liquor in the same. I

Having thus described our invention we claim as new and desire to secure by Le ters Patent- The process herein described of utilizing thewaste liquors of sulfite and soda pulp mill liquor containing salts of organic sulfonic acids with the liquor from the soda-pulp mill containing sodium sulfid, concentrating the neutralized liquor, calcining the concentrated liquor, leaching the residuum obtained thereby, treating the solution thus obtained with 'burnt lime, and draining off the soluble VIGGO DREWSEN. LAURITZ J. DORENFELDT.

Witnesses:

PAUL GOEPEL, HENRY SUHRBIER.

mills,which consists in neutralizing the sulfite- I 

